Scrap Science - 2020-04-09
After making sulfuric acid by diaphragm electrolysis more than a year ago, I've had a few requests to try making nitric acid by the same process, and have decided to give it a go in this video. By electrolysing a solution of potassium nitrate, we slowly generate nitric acid on the anode, as a result of the electrostatic attraction between the anode and the nitrate ion, and the formation of hydrogen ions on the anode surface. Using a semi-permeable diaphragm between the two electrodes, we can isolate the nitric acid we generate, and collect it after running the cell for a day or two. Sadly, testing the current setup for this length of time only yields about 250mL pf nitric acid at a very low concentration (0.7M at best), which is not particularly useful when compared with the concentrated stuff, in fact, to dissolve copper metal I first had to concentrate the acid by a factor of 3. In order to be a viable production method, some changes must be made to the process. Possibly, changing the volumes of the chambers, lengthening the run time, or adding a second diaphragm to prevent the reduction of nitrate ions on the cathode may improve the yield, but maybe I'll try that in another video.
Wonderful! I've been purifying saltpeter which had been crystallizing on a wall of a former pigsty for a while now and I've been looking for something to do with it!
I also wondered what would happen if I were to electrolyze it so yeah, good thinking I guess.
This is going to be great for my diy lab thank you so much
I've been looking for an alternative way to make ammonia... nice to see this....
I love just being part of your journey into amateur chemistry by watching your videos. I do a lot of chemistry which I should create more videos of like you. I'm most obsessed with extracting elements from rocks and minerals, which is actually quite dangerous because of the many regularly encountered unknowns. It's a bit scary having to treat the hazmat as I've identified arsenic and thallium from ores I've dissolved in acids. God only knows what else I have in my bucket of various sealed unknown product containers.
Is there an easy way to extract the elements in cinnabar from everyday stuff?
@Vivi mannequin If you have cinnabar, it is easy enough to extract the mercury. I think it can be displaced using carbon as a reduction agent within a sealed clay vessel. It can also be extracted using acid then cementing the product out by addition of aluminum, zinc or magnesium. Cinnabar tends to carry other contamination products like arsenic, so the mercury needs further purification through distillation. Mercury vapors are really harmful as-is so the toxicity of arsenic probably isn't much of an argument point. Just take the proper precautions as you would with any chemistry experiment to stay safe and avoid contaminating the environment.
@Matthew Wilson How do you displace it with carbon?
@Vivi mannequin I guess the method is to actually roast the cinnabar with quicklime I was thinking of. The easiest way then would be to roast the cinnabar with oxygen to release sulfur dioxide and mercury.
@Matthew Wilson I don't have the equipment to do that though
Great upload as I'm getting back into it so I can stay home and be a chemist 👍 Now is the pot is the semi-permeable membrane? Thanx💖
Yes, you're correct about the clay pot. :)
I finally found an improved but more lengthy process
use a copper anode to produce copper nitrate and continiously remove KOH from the cathode compartment.
make the porous pot area the cathode compartment.
after you obtain copper nitrate crystals from the anode chamber you then run a seperate diapragm cell electrolysis run where you use graphite as the anode and steel or graphite as the cathode and you will produce copper metal in the cathode compartment which you can remove to totally remove and ions in solution to get a very high concentration of Nitric acid.
the cathode compartment ph may drop after some time so a tiny bit of sodium hydroxide may help keep it from becomming acidic if you are using steel as a cathode otherwise if its graphite then there is no problem there.
This method works for sulfuric acid too but sadly not hydrochloric acid
the copper/iron 2 chloride just gets electrolyzed into chlorine sadly
Another option would be to decompose the copper nitrate using heat like NurdRage did in his last video. In fact, the biggest problem was to get the copper nitrate, because he made it from calcium nitrate and copper sulfate, which gives very difficult to filter calcium sulfate.
Also, if you don’t have easy access to HCl, you can always make it from NaCl and H2SO4, as your method works for H2SO4 too.
@GRBTutorials u know after so long ive made a liter of HNO3 so far and guess what my process is.
Well I found a cheap Pt catalyst sold for fireplaces 22 dollars for like A LOT 5 grams of Pt on ceramic wool which makes a volume of like 250cc which means I can make a lot of reactors.
I then created a setup using an ammonia desorber and airline regulator valves to carefully control the gas composition about the catalyst.
Could you use a aluminum cathode to push the reaction forwards by the potassium hydroxide and aluminum reacting to produce sodium aluminate and more hydrogen ions
I'm afraid not, the reaction of aluminium with potassium hydroxide does not produce hydrogen ions, but hydrogen gas instead. The reaction isn't really influenced by the presence of hydrogen ions anyway, it's pretty much just based on how many nitrate ions you can push through the diaphragm.
I must say this guy rly makes science with scrap. Nice work
New favorite Youtuber!Love your vids man keep it up!
Would like to see the difference when using 2 pots instead of one
Brian Coit, Double the amount on nitric acid.
I don't think one would happen,i shall try and infform you all
🙏🙏🙏🙏❤️ GOD BLESSED
Suppose you have the potassium nitrate solution and distilled water at below, or the same level during electrolysis changing or reducing osmotic pressure.
Could using hydrogen peroxide cause it to react instead of the heat?
Yep, probably. Though if your end goal is simply to dissolve copper rather than make copper nitrate specifically, you could also use a mix of peroxide and hydrochloric acid, which also does the trick and is easier to set up.
@Scrap Science I wasn't thinking really about how it would change the cu nitrate in the end since I thought it would just disassociate
At this concentration will it react with steel if so could I supersize this with unused 55 gallon barrels and the largest garden pot I can find
Well, while it would be very likely to react with steel there, you could design the cell such that the outer area of the barrel is the cathode chamber (in fact, making the barrel itself into the cathode would allow for very high current). If you then just generate the nitric acid in the clay pot, you'd be keeping the acid away from the steel anyway.
LOL, I never would have ever thought I'd see the day that a pair of hands could this overact. LOL
Great work, even with the spazzie hands! Thanks for being you!
Yeah, I don't know what my hands were doing in this video, it's so crazy that I can't bring myself to watch it again honestly :)
I've switched up how I film my videos now though, so everything's a lot less hectic these days.
Glad you enjoyed it anyway!
Since you have some Pt on fiber Glas wool
You can oxidize NH3+O2= HNO3+H2O.
And you can get urea for fertilizer and Ca(OH)2+NH2CONH2= 2NH3+CaCO3.
Would you like to revisit this with two clay pots? One inside the other. I think your yeild will improve.
Furthermore, what if you coil the copper cathode around the outside clay pot a few times and place the anode directly in the center.
I hypothesize that:
1) will provide a more uniform electric field around the pots; and
2) a more uniform electric field will help better push and pull on the ions into their seperate containers; and
3) ion penetration will happen over a larger area of both pots reducing the resistance in the cell; and
4) A lower resistance will let you lower the applied voltage and that will improve the efficency.
I'll definitely be revisiting this process in the future, I'm planning on it being a future video of my diaphragm electrolysis series. Two diaphragms instead of one is the plan to improve efficiency.
The shape of the actual electric field itself isn't really a factor on efficiency, as the reaction rate and efficiency are solely determined by the cell current and it's relation to the cell voltage rather than where the ions are moving. You're 100% correct on points 3 and 4 though, plus the effect of lowering current density on the cathode will further lower resistance and increase efficiency.
@Scrap Science I am sooooooo looking forward to your next video.
I think point 3 (ion penetration over a larger area of the pot diaphragm) happens because the geometry creates a shaper field gradient "all around" the cell that better pushes and pulles ions over a larger area and better prevents diffusion mixing.
I'm only a minute or two into this, and while I'm sure the content will be fascinating, I'm getting a headache from all the camera movement.
the video i wanted thank you!!!
I gave this experiment a try, using two small clay pots and a couple of platinum electrodes. Both were the platinum-plated expanded titanium type measuring roughly 4 square inches. I started with a dilute solution of 100G of KNO3 in about 2.5 liters of distilled water, and distilled water in the red clay pots. I used an adjustable digital-display power supply capable of limiting both current and voltage.
I set initial voltage to 8V without a current limit. The anode side became strongly acidic in a very short time once the current ramped up; and the cathode side very strongly basic. My yield of very dilute nitric acid appeared to be fairly pure but with a pink tint probably caused by the material of the pot, and similar in ultimate quantity to yours, after about 40~45 hours of electrolysis. I used the opportunity to experiment quite a bit with voltage and current limits, so it's not possible to give better than a ballpark account of those parameters; I'd say most of the electrolysis was conducted at around 5V and 200mA. I found that if I limited current to 100mA, voltage tended to stabilize at about 3.9V with minimal gas production at the electrodes. Higher current got higher voltage (unless it were limited) and a lot more gas. I stopped the process rather early. I'm sure I did not consume all of the 100grams of KNO3 with which I started. I also boiled down a large volume of water taken from the cathode side, which yielded a gram or so of what must be fairly pure KOH, which of course refuses to dry fully over moderate heat. Incidentally the cathode side didn't appear to lose a significant amount of water.
Likely because my KNO3 wasn't very pure, the KNO3 solution that was NOT inside either of the pots became slimy and cloudy, with a pH of about 9. The KNO3 had come from stump remover, so it contained unknown anti-caking agents. This, and my desire to move on to boiling down my products, prompted me to end the electrolysis early. So I can't really assign anything remotely like a percentage yield.
Presumably this method would produce copper nitrate if a sacrificial copper anode were used. I'm thinking there's a chance that rather than liberating a lot of NO2 as happens when copper is directly added to nitric acid, the NO2 might have a chance to go into solution and thence produce the metal nitrate more efficiently. I'm going to give that a try next. I'll use much purer KNO3. Hopefully the process itself will provide a means to know when the electrolysis is done. I would expect the copper to stop eroding when the KNO3 has been consumed.
Where did you get the pots from?
@Yasyas Marangoz Walmart! It's a seasonal item. About 12cm wide and high. Same as this:
https://www.walmart.com/ip/5-5-Clay-Pots-Great-for-Plants-and-Crafts/150223887
Try mixing calcium nitrate (very easy to find as fertilizer) and oxalic acid directly and you get around 40% conc of nitric. although you will get some junk dissolved in it but you can use the nitric for most things. Although a quick distillation would help it.
Nice
What would be the ratio
After 14:30, try watching this video with the audio muted and pay attention to the hand motions. You'll probably want to scream at the content creator that the beakers aren't going to bite him.
I am designing a process and in a stage I get copper nitrate. This method works for regenerating the nitric acid and separating it from copper?
Yep, any nitrate salt will do. In that case, you’ll also plate the copper metal onto the cathode
You can use Gaseq to calculate the equilibrium yields of NO given compression ratio and
Fuel and air mixture.
The best technique
That cardboard power supply makes me ancy.
But it's eco-friendly and in some cases might even turn surrounding area more futile for local ecosystem
Doesn't the nitric Acid react with the clay ?
Not at these very low concentrations, it would have to be much, much more concentrated for any reaction to occur, and that's if it does react at all, terracotta is surprisingly resistant.
What if I use a lead dioxide anode instead of a carbon or platinum one?
Definitely don’t try that. Lead dioxide, even industrially made ones, are not at all resistant to nitric acid, you’ll quickly end up generating an incredibly toxic solution of lead nitrate. Please don’t poison yourself, carbon/graphite anodes are always a safe alternative.
Great video and explanation. But, boy are you fidgeting. Maybe fewer hand gestures my friend. Still good.
Can't even obtain potassium nitrate over here without going onto a watch list thanks to the IRA.
Which is a shame because nitric is useful for alot of chemistry, gold refinement and etching.
Know of any process to get nitrates for a home chemist in nanny states beyond the birkeland eyde process
The Ostwald process is one possibility. ( https://youtu.be/dMV4-CxCyL0 and https://youtu.be/iaNSH89gpPk )
Ammonium sulfate fertilizer can be used as a source of ammonia, with sodium hydroxide. ( https://youtu.be/gh4gGkk74iU )
nitric acid from Acqua regia? it will be amazing-
If only.
You can use iron anode in KNO3 to make Fe(NO3)3 and make KOH in the cathode compartment. Then take the Fe(NO3)3 solution and distill HNO3 off leaving Fe(OH)3 in the distilling flask.
Nice idea!
I might give that a go at some point, but if we're going as far as distillation anyway, I'll probably just go for distilling the potassium nitrate over sulfuric acid.
You can try electolyzing N2 dissolved in water at 150 PSI. This should give HNO3 at the anode and NH3 and H2 at the cathode compartment. It is a bit dicey doing high pressure electrosis.
Yeah, I'm afraid anything involving high pressure is way beyond my skill set at this stage (probably at all stages honestly).
So is this how titanium nitride coating works? (In it's most basic principle?)
I'm not sure what you mean. I don't think nitric acid or electrochemistry have anything to do with titanium nitride. Or are you referring to something else?
@Scrap Science
I was referring more to the process than the chemicals. As an example, putting a titanium compound in the clay pot, the nitrate in the other container and the ln using the thing I want to coat as the cathode.
But I guess I don't really know how to ask it, because I'm not good with chemistry 🤣🤣🤣
But I appreciate the reply! Thank you very much!
Ah, rightio, I get what you mean now.
This process isn't actually related in that sense. A titanium nitride coating involves a complex sputtering process under vacuum rather than electroplating.
The process you've described would possibly generate titanium nitrate (in solution), but nitride is a completely different story.
@Scrap Science
Thank you! I actually understood that 🤣🤣🤣
Sputtering is similar to what they do with silicon circuits?
And this process is just making a titanium compound (?)
Yep, very similar I'm pretty sure. I don't really understand the process, but from wikipedia:
"pure titanium is sublimed and reacted with nitrogen in a high-energy, vacuum environment," which forms TiN via plasma, which is sputtered as a coating onto the desired part.
If you are real ambitious you can bud a reactor out of pipes
And gun barrels
And steel rods with 3 combustion chambers. One on each end and one at the center. The two pistons come forward to compress the reaction mixture in the center combustion chamber. In this way you can get much higher temperatures. The rapid cooling freezes the NO composition at the higher equilibrium temperature.
11:39 Time to make a new video.
Hi mate, I have another question for you ... I did what you did with the clay pot , and i used Miracle Grow fertiliserI, I have now made Acid in the clay pot as it reacts with baking soda..But there is a number of different chemicals in Miracle Grow. Would this be nitric acid or some other sort of acid ? As my garage now has a strong smell of chlorine. 😣
Glad to know it's working for you.
As for your first question, the membrane is set up such that it is conductive of ALL ions, pretty much any ion can pass through when there is an electric field across the membrane. In this setup, we've constructed the cell so that the anions in the cathode chamber are attracted to the anode, and pass through the pot into the anolyte to form the corresponding acid. When using fertiliser, even if it only says that nitrogen is present as nitrate, it probably contains other ions in there unless it is pure KNO3. As a result, you'll get all those anions (nitrate, sulfate, phosphate, chloride, etc.) forming their corresponding acids as I've described previously (except for the halides, which are oxidised to the halogens).
For your second question, the calcium carbonate works to purify the acid in two steps. First, when an excess of calcium carbonate is added to the crude acid, the calcium will precipitate most of the impurities, leaving a solution of relatively pure calcium nitrate. Sadly, this gets rid of the actual acid, so to regenerate it, you'll need the second step, subjecting the calcium nitrate solution to the clay pot electrolysis once again, generating a purified acid product. While I reckon egg shells will work fine (provided they are dry), you'll need a VERY large amount of both acid and eggshell in order to get a reasonable quantity of purified acid (the efficiency of the electrolysis process is very low, especially when performed twice). You'll probably require weeks worth of electrolysis to get enough product by this method of purification.
Hope this helps.
@Scrap Science Thanks so much for your time in answering this... I have a bag of horse manure , so i will do something with that as well. This has sort of become a challenge to me now just to accomplish making real nitric acid for no other reason now than that.
@Changwei Hsu Yep, that's exactly right.
In fact, copper sulfate and nickel acetate don't even need a membrane to get the job done. When the metal cation has a higher reduction potential than hydrogen (like with copper and nickel), the metal is plated out during simple electrolysis to leave the acid behind, no clay pot required.
@Scrap Science Would salt make hydrochloric acid with the same setup? Also, can the clay pot be reused?
@Changwei Hsu Trying to make hydrochloric, hydrobromic, or hydroiodic acid is a lot trickier with this method. When the halides are present, the anode is able to oxidise them rather than water. So what ends up happening is that elemental chlorine would be formed in the anode chamber of your setup, as the chloride ions would be preferentially oxidised at the anode instead of water (which would have generated the necessary H+ ions for the acid).
The clay pot can definitely be reused. Though if you're setting up for producing different acids with a single pot (ie. you produce sulfuric acid with it on one day, and then on another day you want to produce nitric acid), I'd let the pot soak for a few days in distilled water between runs to minimise contamination.
Do you think Calcium Nitrate would work?
Yep, calcium nitrate will do just as well as any other nitrate salt
I like the video ☺💪👍
what percentage of nitric acid would this be ?
The electrolysis generated a concentration of around 1% or 2% probably
Does it work with amonia nitrate?
Yep, any nitrate salt will do.
If a higher power supply was used would it speed up the process ?
Yep, the reaction rate is proportional to the current through the cell, which in turn is based on voltage. A higher voltage supply (provided it can keep up with the current the cell draws) will make the reaction quicker. However, it will also cause carbon anodes to disintegrate much quicker, but they're cheap so it shouldn't matter too much.
Would ammonium chloride work the same?
To make nitric acid? No, in the best case scenario, you'd end up generating ammonia in the cathode compartment and chlorine gas off the anode (definitely not ideal and dangerous if you don't have a fume hood). Worst case scenario, you'd end up generating small amounts of dangerously explosive compounds such as nitrogen trichloride (this is the main reason why electrolysis of ammonium chloride should always be avoided). In theory, you may get some small yield of nitrates on the anode if the salt is added to the anode chamber initially, but I'd definitely say it's not worth it to try, given the possible dangers.
@Scrap Science Ok thank you
I would like to know how to make sodium thiosulfate please reply or make a video about it
You can also run a high compression diesel engine lean and make NO and then NO+O2+H20 = HNO3.
And use the shaft work to. Drive a generator.
There is a free program called gaseq you can download from the internet. It calculates temperatures
Pressures
Equilibrium constants
Reaction and product
Concentrations.
Written by rocket scientists in Fortran.
For making sulfuric, nitric, phosphoric, acetic, hydrochloric, etc, if using the copper salts of those, is the clay pot still required? i.e. copper sulfate, copper phosphate, copper acetate, copper chloride, etc
If it isn't required when using copper salts, then is there an upper limit?
For sulfuric:
A clay pot is not required, as per my video on that topic. An upper limit exists due to the drastically decreased solubility of copper sulfate as the concentration of acid increases. I’d estimate the limit to be about 50-60% (acid concentration) but I’ve never experimented to see how far it can go.
For nitric:
A clay pot is required, as the generated solution of nitric acid should not be allowed to come into contact with the cathode (which would react with the acid to form unwanted side products).
Using copper nitrate really isn’t practically different to using any other nitrate for this process.
For phosphoric:
A clay pot is not required. This would work similarly to sulfuric acid generation, and would likely have an upper limit for the same reason. I’m not sure what kind of max concentration would be achievable for it though, I’ve never experimented with that reaction.
For acetic:
A clay pot is not required. An upper limit probably exists here from the fact that at high acid concentrations, the acid will react on the anode to form ethane and CO2. It also might suffer from the same low solubility problems as the sulfuric acid process, but I’m unsure because acetic acid is nowhere near as strong as sulfuric.
For hydrochloric:
You cannot make hydrochloric acid directly by electrolysis of a chloride salt, regardless of whether or not you use a clay pot. Chloride will preferentially react on the anode to form chlorine rather than stay in solution and allow the acid to be generated.
The only effective way to do it (somewhat indirectly) by electrolysis is to react chlorine and hydrogen gasses (made by clay pot electrolysis of NaCl) together, forming HCl gas. This reaction is very difficult to do safely however, as it is often explosive. I’ll also hopefully cover the reaction in a future video.
Couple of points which may help out. The ionic exchange is being drastically limited by the lack of variable voltage and the distribution of current across the anode and cathode. By this I mean when current is low because of the lack of electrolytes in the distilled water it helps to increase the voltage a little to get electron excitement working quicker. When current starts flowing you can then reduce the voltage well below 12vdc. This is slower but it stops cathode and anode annihilation. Professional electrolysis is usually done at about 1.5vdc to avoid cathode/anode annihilation but it also involves better separation materials rather than clay. The shape of the anode and cathode are critical for even current distribution through the solutions otherwise you'll annihilate your equipment. Instead of dropping the anode and cathodes into the solution vertically and creating a concentration in one particular area, consider horizontally mounted rods. Take the graphite rods and drill 4 holes in them evenly spaced half way through and insert graphite pegs into the holes. Then split the source wire for the cathode into a 1 into 4 configuration and the same for the anode, connect each wire to each peg. This distributes the current and voltage across a larger surface area and increases ionic exchange significantly. Because you have a greater surface area to play with, current can be increased without causing too much damage to the graphite. Voltage can also be increased accordingly because current and voltage are distributed evenly and voltage nodes will not appear on the graphite. Pulse width modulation is also a great option for this type of work, look into that.
the decomposition of HNO3 on the anode makes this process not worth it and I do have proper ion exchange membranes.
I instead opted for the oxidation of ammonia since I found a cheap source of Pt catalyst ready made for less than 25 USD for 250cc of catalyst.
As a general note for others, anode wear can be mitigated by controlling the current density the anodes see. A starting point for graphite I like is around 15 mA/sq. cm. On little cylindrical anodes like these though, this reaction would be taking weeks. I'm using blocks that are a few hundred square centimeters. I think that Scrap Science is just willing to let the wear happen to get reasonable reaction speeds.
Nice video!!
agreed! you inspired me to make my own channel
@Davis Dean yea your channel has potential just keep uploading and keep up the good work
Braveskin - 2020-04-09
Good stuff, I've been enjoying your videos a lot. Thanks for sharing!